In this proposal, we provide evidence that the NAD-dependent deacetylase SIRT1 modulates NF-kappa B transcription in non-small cell lung cancer (NSCLC) cells. Data presented in this proposal demonstrate that SIRT1 deacetylates lysine 310 of RelA/p65 subunit of NF-kappa B to inhibit transcription. We find that SIRT1 and NF-kappa B can repress the PTEN promoter through this novel mode of transcriptional repression. The overall goal of the proposal is to understand the mechanisms by which SIRT1 represses NF-kappa B-dependent transcription and elucidate whether this mode of regulation may account for the silencing of the PTEN gene. This hypothesis will be addressed in 2 specific aims. Aim1 will establish the mechanisms by which SIRT1 regulates NF-kappa B transcription. Experiments will use pharmacological agents that regulate SIRT1 activity as well as SIRTl-specific siRNA to determine the role of this deacetylase in regulating NF-kappa B transcription. Aim2 will elucidate whether PTEN tumor suppressor gene is regulated in a SIRT1/NF-kappa B-dependent manner. Experiments will include performing chromatin immunoprecipitation and transient reporter assays to determine if the PTEN gene is a target of SIRT1-mediated repression.